'tastiness' originates from English, specifically formed from the adjective 'tasty' plus the suffix '-ness'. 'Tasty' itself is built on the root of the verb 'taste', which comes from Old French 'taster' (from Vulgar Latin *tastare), where the root 'tast-' meant 'to touch, try, taste'.

'tastiness' developed in modern English by adding the nominalizing suffix '-ness' to 'tasty'. 'Taste' came into English via Old French 'taster' and Vulgar Latin *tastare; 'tasty' was later formed from 'taste' + '-y', and 'tastiness' followed as the noun form.

Initially related to the basic idea of 'being able to be tasted' or 'the act of tasting', it evolved into the specific quality sense of 'having a pleasant flavor' now expressed by 'tastiness'.